1. Field of the Invention
The present invention relates to a semiconductor integrated circuit including a tungsten silicide nitride (WSiN) film formed on a semiconductor substrate and a method for producing the same.
2. Description of the Related Art
In order to realize a temperature-compensating function by compensating for temperature characteristics of a semiconductor integrated circuit (hereinafter, also simply referred to as an "integrated circuit"), a thermal resistor is generally used. Hereinafter, a prior art semiconductor integrated circuit using a thermal resistor will be described.
Specifically, a thermal resistor made of a metal oxide, or the like, having a negative temperature coefficient is provided as a thermistor resistor at an external position of an integrated circuit in such a manner as to be thermally connected to the integrated circuit, whereby a temperature-compensating function is realized by utilizing the changes in resistance of the thermistor resistor due to the increase in temperature. Japanese Laid-open publication No. 2-44701 discloses a method in which a thermal resistor made of a tungsten nitride (WN) film is provided in an integrated circuit, and the resistance of the resistor is adjusted by annealing.
However, with the structure in which a thermistor resistor is externally provided to an integrated circuit, the size of the thermistor resistor is generally almost the same as that of the integrated circuit, so that the size of an entire circuit obtained by using the integrated circuit becomes large. Furthermore, according to the conventional technique, it is difficult to produce a thermistor resistor having a desired temperature coefficient with good precision, and the resultant thermistor resistor has temperature coefficient characteristics varied in a wide range. Therefore, it is required that a thermistor resistor having appropriate temperature coefficient characteristics be selected.
According to the above-mentioned method in which a thermal resistor made of a WN film is provided in an integrated circuit, and the resistance of the resistor is adjusted by annealing, the entire semiconductor wafer is heated by annealing. Therefore, there is a possibility that other circuit elements formed on the wafer are subject to damage during annealing. Furthermore, the changes in wafer temperature may be delayed in terms of time at the beginning and ending of heating during annealing, which prevents the resistance from being adjusted with good precision. In addition, it is difficult to complete the adjustment of the resistance within a short period of time.
In addition, although the WN film can be formed so as to have a negative temperature coefficient suitable for a thermistor resistor, the temperature coefficient cannot be set to be large enough. Furthermore, depending upon the production conditions, the temperature coefficient becomes positive, causing problems with using a thermistor resistor which should exhibit a temperature-compensating function.